Old news, but worth posting about:
CSMonitor: Asteroid headed our way:
>NASA researchers have begun considering whether the US needs to tag the asteroid, known as 99942 Apophis, with a radio beacon before 2013. Timing is everything, astronomers say. If officials attempt to divert the asteroid before 2029, they need to nudge the space rock’s position by roughly half a mile – something well within the range of existing technology. After 2029, they would need to shove the asteroid by a distance as least as large as Earth’s diameter. That feat would tax humanity’s current capabilities.